Definition of red ensign in English:

noun

As well as being the senior ensign of the King's ships, the red ensign was also worn by merchant ships.

The use of special red ensigns with their badge in the fly has in the past been authorised for a number of yacht clubs, but it is now the policy not to extend this privilege, except in the most exceptional circumstances.

The idea of adding the EU's emblem to the red ensign was rejected in a vote in Strasbourg on tighter controls on maritime safety.